Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/80—Processes for incorporating ingredients
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/16—Antifouling paints; Underwater paints
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/14—Paints containing biocides, e.g. fungicides, insecticides or pesticides
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/65—Additives macromolecular

Definitions

• the present invention relates to a process for preparing an antimicrobial coating composition, an antimicrobial coating composition and use thereof to confer antimicrobial properties to the surface of a substrate.
• antimicrobial coatings particularly paints, which act either by preventing the adhesion of microorganisms or by reducing their proliferation through a cytotoxic action (biocidal action).
• Antimicrobial coatings are generally obtained by applying compositions, generally in liquid form, to the coating surfaces.
• a coating composition contains: (1) at least one film-forming agent (also called binder), (2) volatile components (e.g. solvents), (3) pigments and (4) additives.
• the antimicrobial effect is generally achieved by incorporating one or more additives with antimicrobial properties into the compositions.
• the antimicrobial efficacy of the coating depends, among other factors, on the compatibility of the antimicrobial agent used with the other components of the coating composition, in particular, on its compatibility with the film-forming agent.
• the antimicrobial agent can be easily dispersed in the coating composition and that the resulting dispersion is sufficiently stable over time, i.e. it does not undergo phenomena of phase separation or sedimentation for a sufficiently long period of time.
• graphene-based materials in particular graphene in oxidized form (graphene oxide), are known and used as antimicrobial agents in antimicrobial coating compositions.
• graphene oxide graphene oxide
• An example of such use of graphene is the commercial product "Dr. Wall", from the company Graphene.CA, USA, a water-based acrylic paint containing a combination of graphene and TiCy.
• a limitation of the coating compositions containing graphene consists in the limited antimicrobial efficacy of the obtainable coatings, both in terms of reduced antimicrobial action and in terms of duration of this action over time.
• compositions which have a more effective and prolonged antimicrobial action over time than the compositions of the prior art.
• antimicrobial coating compositions can be prepared easily, quickly and economically.
• the aqueous dispersion of graphite comprises at least one oxidizing agent (e.g., hydrogen peroxide) and is subjected to a high shear homogenization step (equal to or greater than 1000 rpm) during which graphite exfoliation takes place with formation of graphene nanoplates and concomitant oxidation of graphene to graphene oxide (hereinafter also referred to as GO alone).
• oxidizing agent e.g., hydrogen peroxide
• Coating compositions obtained from the aforementioned aqueous dispersion of graphene oxide can be applied to the surface of a substrate to form a coating film whose antimicrobial action is superior in terms of biocidal efficacy and prolonged than that of compositions known in the state of the art.
• the present invention relates to a process for preparing an antimicrobial coating composition according to claim 1.
• the present invention relates to an antimicrobial coating composition obtainable by the aforementioned process, in accordance with claim 13.
• the present invention relates to the use of an antimicrobial coating composition according to claim 14 to impart antimicrobial properties to a substrate.
• the present invention relates to a method for imparting antimicrobial properties to a substrate according to claim 15. Further features of the above aspects of the present invention are defined in the dependent claims.
• compositions according to the present invention may "comprise”, “consist of” or “consist essentially of the” essential and optional components described in the present description and in the appended claims.
• the expression “essentially consists of” means that the composition or component may include additional ingredients, but only to the extent that the additional ingredients do not materially alter the essential characteristics of the composition or component.
• graphene and graphene oxide are to be understood according to the definitions reported in ISO/TS 80004-13:2017 (Nanotechnologies — Vocabulary — Part 13: Graphene and related two- dimensional (2D) materials).
• graphene includes, in addition to monolayer graphene, the materials formed by 2 to 10 superimposed layers of graphene, such as bilayer graphene, "few-layer graphene” composed of three to ten layers of graphene and graphene nanoplates consisting of superimposed layers of graphene and having a thickness in the range from 1 nm to 3 nm and lateral dimensions from 100 nm to 100 micrometres.
• antimicrobial refers to a substance capable of inactivating any biochemical function of microorganisms (understood as organisms sized on the micrometre scale, such as fungi, bacteria and viruses).
• the molecular weights of the polymeric substances are expressed as mean weight MW, determined by Gel Permeation Chromatography (GPC).
• GPC Gel Permeation Chromatography
• the process of preparing the antimicrobial coating composition comprising the following steps in sequence: a. providing an aqueous dispersion comprising graphite, at least one oxidizing agent and optionally at least one antimicrobial agent; b. subjecting the aqueous dispersion from step a to high shear homogenization by mixing said dispersion at a mixing speed equal to or greater than 1000 rpm, to obtain an antimicrobial aqueous dispersion comprising graphene oxide; c. mixing the aqueous antimicrobial dispersion comprising graphene oxide with at least one film-forming agent to obtain the antimicrobial coating composition.
• the graphite used in step a is preferably high surface area graphite (HSAG) with high crystalline order within the structural layers.
• HSAG high surface area graphite
• graphite has a surface area in the range from 200 to 500 m 2 /g, as determined by the ASTM D 6556 method.
• graphite has a turbostratic structure with a relatively low number of stacked layers, e.g. 30 to 40 (approximately 35).
• the lateral dimensions of the graphitic layers are about 300 - 400 nm. The dimensions can be determined, for example, as described in Biomacromolecules 2017, 18, 3978-3991.
• Graphite preferably has a carbon content equal to or greater than 99% by weight.
• the chemical composition of graphite determined by elemental analysis, may be as follows: carbon (99.5% weight/weight), hydrogen (0.4% weight/weight), nitrogen 0.1% (weight/weight).
• the concentration of graphite in the aqueous dispersion of step a is preferably in the range from 0.1 % to 10 %, more preferably in the range from 0.5 % to 5 %, even more preferably in the range from 0.8 % to 2 %, the aforesaid percentages being percentages by weight referred to the weight of the dispersion.
• the aqueous graphite dispersion comprises at least one oxidizing agent to oxidize the graphene produced by exfoliation to graphene oxide.
• the oxidizing agent can be selected without any particular limitation from those generally used in the state of the art for the preparation of graphene oxide.
• the oxidizing agent is selected from: oxygen, hydrogen peroxide, air in the presence of potassium hydroxide, nitric acid, tert-butyl peroxide, m-chloroperbenzoic acid, ozone, sulphuric acid, permanganate ion (e.g. KMnCq), chromate ion (K2Cr2C>7), hypochlorite ion and their mixtures.
• the oxidizing agent is selected from: oxygen, hydrogen peroxide, air in the presence of potassium hydroxide, tert-butyl peroxide, m- chloroperbenzoic acid, ozone, chromate ion (K2Cr2C>7), hypochlorite ion and their mixtures.
• the oxidizing agent is selected from: oxygen, hydrogen peroxide, tert-butyl peroxide, m-chloroperbenzoic acid, ozone, chromate ion (K2Cr2C>7), hypochlorite ion and their mixtures.
• the oxidizing agent is preferably hydrogen peroxide (H2O2), optionally mixed with acetic acid.
• the acetic acid that is added to H2O2 can bring several advantages, such as: 1) transferring acidic protons useful for salifying the amino groups of chitosan;
• the acetic acid in combination with H2O2 can form peracetic acid, which is extremely active both as an oxidizing agent and as an anti-bacterial agent.
• hydrogen peroxide is used in the form of an aqueous solution containing a concentration of H2O2, expressed as percentage by weight of H2O2with respect to the weight of the solution, in the range from 0.5% to 30%, preferably from 2% to 20%, even more preferably 5% to 15%.
• the oxidizing solution may also contain acetic acid, preferably in a molar ratio H 2 0 2 :CH 3 C00H in the range 30:0.01, preferably 20:0.05, even more preferably 10:0.1.
• the water of the aqueous dispersion is demineralized water and/or industrial and/or drinking water.
• the demineralized water has an electrical conductivity in the range from 30 microS/cm to 100 microS/cm, preferably in the range from 45 microS/cm to 50 microS/cm.
• the industrial and/or drinking water has an electrical conductivity in the range from 3000 microS/cm to 100 microS/cm, preferably in the range from 500 microS/cm to 50 microS/cm.
• water is present in the antimicrobial dispersion composition in an amount in the range from 70 % to 98 %, preferably 80 % to 95 %, even more preferably 88 % to 92 %, the aforesaid percentages being percentages by weight referred to the weight of the antimicrobial coating composition.
• High shear homogenization refers to mixing the graphite dispersion at a mixing speed equal to or greater than 1,000 rpm, preferably equal to or greater than 2,000 rpm, more preferably equal to or greater than 3,000 rpm.
• the mixing speed is equal to or less than 10,000 rpm, preferably equal to or less than 9,000 rpm, plus preferably equal to or less than 6,000 rpm.
• the mixing speed is in the range 4,000 rpm - 9,000 rpm, more preferably in the range 5,000 rpm - 7,000 rpm.
• rotor-stator mixers comprise a mixing element (rotor) at high speed (typically 10 to 50 m-s- 1) and a fixed element (stator) which are positioned in close proximity to each other so that the gap between the end of the rotor and the walls of the stator is very narrow, typically from 100 micrometres to 3 millimetres.
• the duration of the high shear homogenization step is preferably in the range from 1 hour to 24 hours, more preferably in the range from 5 to 10 hours, even more preferably in the range from 8 to 9 hours.
• an aqueous dispersion comprising graphene oxide in the form of nanoplates.
• the antimicrobial coating composition comprises graphene oxide in an amount in the range from 0.1% to 10%, preferably in the range from 0.5% to 5%, more preferably in the range from 0.8% to 2%, said percentages being percentages by weight referred to the weight of the antimicrobial coating composition.
• the dispersion of graphene oxide is homogeneous and stable, with no phase separation or sedimentation observed over a relatively long period of time (at least one month) under conditions at room temperature and atmospheric pressure.
• the graphene oxide dispersion is compatible with the addition of one or more film-forming agents, i.e. it can be mixed with one or more film-forming agents in a wide range of concentrations.
• the film-forming agent has the function of promoting the formation and adhesion of a coating film on the surface of the substrate which is to be made antimicrobial.
• film-forming agents such as polymeric resins generally used in the preparation of coating compositions, varnishes, paints, enamels, etc., may be used.
• Non-limiting examples of film-forming agents which may be used for the purposes of the present invention are: acrylic resin, vinyl resin, styrenic resin, alkyd resin, epoxy resin, polyester resin, polyvinyl acetate resin and their combinations.
• the film forming agent is preferably present in an amount in the range from 1% to 99%, more preferably in the range from 1.5% to 75%, even more preferably in the range from 3% to 50%, said percentages being percentages by weight of the dry resin referred to the weight of the antimicrobial coating composition.
• steps a - c are carried out at a temperature in the range from 25°C to 90°C, more preferably in the range from 35°C to 85°C, even more preferably in the range from 55°C to 80°C.
• steps a - c are carried out at an absolute pressure in the range from 0.5 bar to 2 bar, more preferably in the range from 0.8 bar to 1.2 bar, even more preferably at atmospheric pressure.
• the antimicrobial coating composition comprises at least one additional antimicrobial agent other than graphene oxide.
• the antimicrobial coating composition comprises at least two further antimicrobial agents, other than graphene oxide.
• the antimicrobial agent may be selected from, for example: quaternary ammonium salt; polyglycol having a molecular weight in the range from 200-12,000 g/mol; polysaccharide having antimicrobial properties, preferably chitosan, galactan, mannan and laminarine; metal ion having antimicrobial properties, preferably silver ions, sodium ions and zinc ions; chlorinated isothiazole; and their mixtures.
• the at least one antimicrobial agent comprises: quaternary ammonium salt, preferably benzalkonium salt; molecular weight polyglycol in the range 200 - 12,000 g/mol; silver ion.
• the quaternary ammonium salts can be selected from quaternary ammonium salts containing benzyl groups and having hydrocarbon chains of various lengths (e.g. benzalkonium chloride, benzethonium chloride, benzalkonium bromide).
• the quaternary ammonium salts have the following general formula I wherein:
• Ri and R2 are independently an alkyl group containing a number of carbon atoms comprised between 1 and 10, preferably between 1 and 5 and even more preferably between 1 and 2;
• - R3 is an alkyl group containing a number of carbon atoms comprised between 1 and 10, preferably between 1 and 5 and even more preferably between 1 and 2;
• - n is an integer comprised between 1 and 20, preferably between 6 and 15 even more preferably between 8 and 12;
• - X represents a halogen counterion selected from fluorine, chlorine, bromine, iodine, preferably chlorine and bromine, even more preferably chlorine.
• quaternary ammonium salts have a polymeric structure.
• An example of such polymeric salts are polydiallyldimethylammonium halide compounds having the following general formula II wherein:
• Ri and R2 are an alkyl group containing a number of carbon atoms from 1 to 10, preferably from 1 to 5 and even more preferably from 1 to 2;
• - n is an integer comprised between 100 and 3000, preferably between 500 and 2500 even more preferably between 1000 and 2000;
• - X represents a halogen counterion selected from fluorine, chlorine, bromine, iodine, preferably chlorine and bromine, even more preferably chlorine.
• the molecular weight Mw of the salts of formula II is preferably comprised between 20,000 g/mol and 1,000,000 g/mol, preferably between 80,000 and 600,000 g/mol more preferably between 200,000 and 350,000 g/mol.
• the polyglycols usable as antimicrobial agents preferably polyethylene glycol, have a molecular weight Mw comprised between 200 g/mol and 12,000 g/mol, preferably between 250 and 6,000 g/mol, more preferably between 300 and 3,000 g/mol.
• the polysaccharides having antimicrobial properties usable for the purposes of the present invention are preferably selected from: chitosan, galactan, mannan, laminarine and their mixtures. These compounds preferably have a molecular weight Mw comprised between 50,000 g/mol and 500,000 g/mol, more preferably between 150,000 and 350,000 g/mol, even more preferably between 190,000 and 310,000 g/mol.
• Metal ions having antimicrobial properties are preferably selected from: silver ions, sodium ions, zinc ions and copper ions, more preferably selected from silver ions, sodium ions and copper ions.
• these ions are present in the antimicrobial coating composition in the form of corresponding metal salts, such as nitrate salts, chlorinated salts, acetate salts and sulphodiazines.
• sulphodiazine salts are compounds with the following general formula III
• - Ri is equal to hydrogen or an alkyl group containing a number of carbon atoms from 1 to 10, preferably from 1 to 5, even more preferably methyl;
• - M is selected from silver, zinc and sodium, - n is either 1 or 2, depending on the valence of the metal counterion M.
• the metal salts can be used as such, in the form of an aqueous solution or solutions in water-soluble solvents based on alkanolamines (e.g. ethanolamine) or diamines (e.g. ethylenediamine).
• alkanolamines e.g. ethanolamine
• diamines e.g. ethylenediamine
• the metal ions are used in combination with at least one polysaccharide, for example of the type described above.
• the polysaccharide is added to the solution containing the metal ions in an amount in the range from 0.2% to 5%, preferably 0.3% to 4%, even more preferably 0.5% to 2%, the aforesaid percentages being percentages by weight referred to the weight of the solution.
• the chlorinated isothiazoles are preferably selected from: 5-chloro-2-methyl-2H-isothiazol-3-one and 2-methyl-2H-isothiazol-3-one.
• the isothiazolinone compounds can be selected, for example, from those with the following general formula IV
• the isothiazolinone compound is benzisothiazolinone .
• the antimicrobial agent used in combination with graphene oxide is present in the antimicrobial aqueous dispersion in an overall amount in the range from 0.1 % to 20 %, more preferably in the range from 0.5 % to 10 %, the aforesaid percentages being percentages by weight referred to the total weight of the antimicrobial aqueous dispersion.
• the weight ratio of the total weight of the antimicrobial agent to the graphene oxide in the coating composition is in the range from 0.01 to 5, more preferably 0.05 to 2, even more preferably 0.08 to 0.15.
• the antimicrobial agent may be used pure or in the form of an aqueous solution, the latter preferably at a concentration, expressed as percentage by weight of the antimicrobial agent with respect to the weight of the solution, in the range from 20% to 90%, preferably in the range from 30% to 80%, even more preferably in the range from 40% to 60%.
• the aqueous or water- soluble solvent solution of the antimicrobial agent preferably has a concentration, expressed as percentage by weight of the metal salt with respect to the weight of the solution, in the range from 0.1% to 3%, preferably in the range from 0.2% to 2%, even more preferably in the range from 0.3% to 1.5%.
• the aqueous solution of the antimicrobial agent preferably has a concentration, expressed as percentage by weight of the polysaccharide with respect to the weight of the solution, in the range from 0.3% to 3%, preferably in the range from 0.5% to 2%, even more preferably in the range from 0.8% to 1.5%.
• the solution containing the polysaccharide or the metal salt is acidified with an amount of glacial acetic acid, expressed as percentage by weight with respect to the weight of the polysaccharide solution, in the range from 1% to 3%, preferably in the range from 0.5% to 2%, even more preferably in the range from 0.1% to 1%.
• the antimicrobial coating composition comprises one or more antimicrobial agents selected from: benzalkonium salts, chitosan and silver ions.
• the antimicrobial coating composition contains all three of the aforesaid antimicrobial agents.
• This combination of antimicrobial agents allows to obtain a coating composition having antimicrobial efficacy against a wide range of microorganisms.
• the antimicrobial agent can be added, indifferently, to the aqueous dispersion containing graphite in step a, in the dispersion containing graphene oxide obtained in step b or in both.
• the antimicrobial agent can be added in the form of an aqueous solution. When two or more antimicrobial agents are present, they can be added together or separately, each being able to be dosed in one or more aliquots.
• the addition of the antimicrobial agent is preferably followed by a high- shear homogenization treatment of the resulting dispersion, e.g. under the conditions described above for step b.
• the antimicrobial coating composition according to the present invention optionally comprises conventional additives of the type generally employed in the formulation of coating compositions, such as, for example, colouring agents (pigments or dyes), solvents, coalescing agents, surfactants, thickeners, rheology modifiers, compatibilizing agents and the like.
• colouring agents pigments or dyes
• solvents such as, for example, solvents, coalescing agents, surfactants, thickeners, rheology modifiers, compatibilizing agents and the like.
• the graphene oxide (GO) of the present invention which is an "edge oxidized” graphene oxide (EOGO)- does not undergoes any reaction of chemical reduction, functionalization, grafting, carboxylation, formation of composite/complex or the like when it is in the presence of the other ingredients used in the present composition such as, for example, antimicrobic agents, film-forming agent, acetic acid.
• EOGO edge oxidized graphene oxide
• the process for preparing the antimicrobial coating composition according to the present invention can be carried out with conventional devices and equipment known to the person skilled in the art.
• the components of the aqueous dispersion prepared in step a can be mixed in any order.
• polysaccharides in particular the chitosan
• quaternary ammonium salts in particular benzalkonium salts
• the exfoliation step is conducted in the presence of at least one polysaccharide, preferably chitosan.
• the quaternary ammonium salt preferably benzalkonium salt, is added to the dispersion after the graphite has been at least partially exfoliated.
• the antimicrobial coating composition according to the present invention may be used to impart antimicrobial properties to the surface of a substrate.
• the composition can be applied with a technique suitable for depositing a liquid coating composition on the surface of a substrate among those generally used in the painting sector, such as by spraying, dipping or by means of a brush.
• the liquid phase contained in the coating composition is evaporated to form a properly cured and dry coating film on the substrate.
• evaporation of the liquid phase is achieved by exposure to air, at room temperature or above.
• the coating composition can be dried in an oven.
• substrates coatable with the antimicrobial coating composition of the present invention are surfaces of plastic, metal, wood, concrete, stone, polycarbonate, plexiglass, PVC, latex, ceramics and the like.
• the coating composition according to the invention can also be applied to previously coated substrates, for example with varnishes, paints, lacquers and other types of coatings.
• the antimicrobial efficacy of the compositions according to the present invention can be measured in terms of the reduction in the total number of living microbes in contact with the antimicrobial coating.
• the antibacterial efficacy can be determined, for example, by means of the ASTM E2180 - 18 method.
• the coating compositions of the present invention can be used against potentially pathogenic microorganisms that are present in the environment.
• Microorganisms against which the antimicrobial coating composition is effective include fungi, algae, bacteria and viruses.
• fungi are: Aspergillus niger and Penicillium funiculosum.
• bacteria are: Gordonia amicalis, Microbacterium hydrocarbonoxidans, Pseudomonas taiwanensis, Pseudomonas resinovorans and Escherichia coli.
• Further pathogenic bacteria on which the coating compositions of the present invention may be effective are: Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium, Streptococcus mutans, Staphylococcus epidermidis, Vibrio harveyi and Enterococcus faecalis.
• the coating compositions are also effective against viruses.
• Viruses are small infectious agents (from 0.02 pm up to a maximum of 1 pm) consisting of biological material that are unable to live or reproduce autonomously except from within a host cell whose functional mechanisms they exploit. Examples of viruses are: Coronavirus, in particular, the Sars-Cov2 virus.
• the antiviral efficacy of the coating compositions can be determined for example as indicated by the ISO 21702:2019 standard "Measurement of antiviral activity on plastics and other non-porous surface”.
• the graphite used is High Surface Area Graphite (HSAG) Nano 27 from Asbury Graphite Mills, Inc. (Asbury, NJ, USA).
• HSAG High Surface Area Graphite
• Graphite has the following characteristics:
• the antimicrobial efficacy of a coating obtained with the above compositions was tested in accordance with the ASTM E2180 - 18 method.
• the antiviral efficacy was instead tested in accordance with ISO 21702:2019 “Measurement of antiviral activity on plastics and other non-porous surface " with some modifications as described below.
• each coating composition including the compositions used for comparative purposes, was deposited on a microscope slide, which was previously scratched (rubbed with sandpaper), flamed, sterilised with ethanol and coated with the same film forming agent present in the coating composition.
• two depositions per day (six hours apart) were carried out for three consecutive days inside an aspirated hood.
• the test according to ASTM E2180 - 18 was conducted on four different bacterial species belonging to risk class 1 (not dangerous to human health), of which two gram-positive and two gram-negative, in order to verify the antimicrobial efficacy of the coatings on bacteria with two different cell wall structures.
• the 4 bacterial strains used are: Gordonia amicalis and Microbacterium hydrocarbonoxidans (Gram+); Pseudomonas taiwanensis and Pseudomonas resinovorans (Gram-).
• the antibacterial efficacy was determined by evaluating the reduction in the number of viable bacteria in the sample with the antimicrobial coating compared to a control sample without the coating according to the following process.
• CFU viable cells
• the seeded plates were left at room temperature for a period of not less than 1 week. After this period, the plates were checked and the colony count (CFU) was carried out on the most suitable dilutions for the purpose.
• CFU colony count
• control sample consisting of the slide coated with only the film-forming agent (primer A or B), corresponding to the film-forming agent present in the antimicrobial coating composition.
• control sample consisting of the slide coated with only the film-forming agent (primer A or B), corresponding to the film-forming agent present in the antimicrobial coating composition.
• Vero E6 cells monkey renal epithelial cells
• DMEM medium 10% heat- inactivated foetal bovine serum, 2 mM glutamine, 100 units/ml penicillin, 100 pg/ml streptomycin were added.
• SARS-CoV-2 was isolated from 500 m ⁇ nasal swab, inoculated onto Vero cells at 80% confluence; after 3 hours incubation at 37 °C with 5% CO2 , the inoculum was removed and the cells were incubated in the medium for 72 hours until the development of a clear cytopathic effect (CPE).
• CPE clear cytopathic effect
• SARS-CoV-2 was concentrated with PEG, following the manufacturer's instructions and the viral titre was assessed by Plaque assay method, using dilutions from 10 1 to 10 9 .
• the complete nucleotide sequence of the SARS- CoV-2 strain thus isolated has been deposited at the Gen Bank, NCBI (accession number GeneBank: MT748758)
• the antiviral test area consisting of a square of (25 ⁇ 2) mm x (25 ⁇ 2) mm was selected on the slide.
• each sample was sterilised by exposure to UV radiations for 20 minutes under a laminar flow hood to eliminate any potential bacterial contamination, and then deposited in a petri dish.
• test was carried out in the following way. A volume of 0.07 ml of viral suspension (9 xlO 5 PFU/ml) was placed on the sample of the material to be tested. The viral inoculum was covered with a 25 x 25 mm film and the samples were incubated for 2 to 4 hours at 25°C.
• the Plaque assay was performed in 6-well plates by assessing the presence of virus in the SCDLP medium recovered from the Petri dishes. For each treatment 3 serial dilutions 1 to 10 were made in complete medium for Vero E6 cells and 0.4 ml of each dilution were added to the cell monolayer, in duplicate. After 2 hours, the inoculum was removed, the cells were washed with 2 ml of medium and covered with 0.3% agarose dissolved in complete medium. After 48 hours incubation at 37 °C with 5% CO2, the cells were fixed with 4% formaldehyde and, after removal of the agarose layer and washing, they were stained with methylene blue. The plaques were counted and the results expressed as Plaque Forming Units (PFU) per ml.
• PFU Plaque Forming Units
• the infectivity of the recovered virus was determined using the following formula:
• N (14xCxDxV) / A
• N is the infectivity of the virus recovered per cm 2 of samp1e
• C is the average number of plaques counted in the two wells of the duplicate
• D is the dilution factor for the counted wells
• V is the volume of SCDLP broth added to the sample, in ml
• A is the surface of the covering film, in cm 2 .
• the antiviral activity was calculated using the following formula:
• R is the antiviral activity
• Ut is the average log of the number of plaques (in PFU/cm 2 ) of the reference sample (primer-only coating, after 2 or 4 hours); At is the average log of the number of plaques (in
• Coating compositions The coating compositions were prepared using a
• Silverson L5M-A rotor-stator homogenizer equipped with an AISI 316 stainless steel head, 290 mm long, 57 mm maximum diameter.
• the apparatus comprises a glass or steel vessel of variable volume (500 - 2000 ml) in which the liquid dispersion to be homogenized in order to obtain the antimicrobial aqueous dispersion containing graphene oxide was loaded.
• Comparative 1 preparation of the slide with Adesital GS primer
• a suitable amount of Adesital GS primer was deposited on microscope slides prepared as described in step 2 above.
• Comparative 2 preparation of the slide with San Marco primer
• Comparative 4 preparation of HSAG graphite mixture and Adesital GS commercial primer (28PN/20/1)
• a suitable amount of HSAG graphite described in point 1 was mixed at 50% by mass with 50% by mass of Adesital primer.
• the dispersion thus obtained was mixed by magnetic stirring for about six hours and then deposited on microscope slides prepared as described in point 2 above.
• Example 1 synthesis of dispersion 01 (015PN/20/1 reference bactericidal test with Adesital Primer;
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 2 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70°C.
• a second aliquot of hydrogen peroxide (40.1 g) is added while mixing for a further two hours.
• a mixture of chitosan (0.43 g), demineralized water (50.1 g) and glacial acetic acid (0.09 g) is added.
• the stirring conditions are maintained for a further two hours at an autogenous temperature value of about 60°C.
• This nanodispersion after the addition of an amount of Adesital primer equal to 5 % by weight of the whole mixture, is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on microscopy slides are carried out, as described in point 2. Once the depositions have been carried out on the slide with the nanodispersions, it is allowed to dry for about 12 hours in order to favour the fixation of the nanodispersion on the glass surface. The slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• the nanodispersion described above after adding an amount of San Marco primer equal to 5 % by weight of the whole mixture, is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on microscopy slides are carried out, as described in point
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 2 synthesis of dispersion 02 (OIbRN/20/l- ⁇ reference bactericidal test with Adesital Primer; 022PN/20/1 reference bactericidal test with San Marco Primer)
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 2 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70°C.
• a second aliquot of hydrogen peroxide 30 % weight/weight Sigma Aldrich (40.4 g) is thus added, in which 0.50 g of solid silver nitrate Sigma Aldrich is dissolved.
• Mixing is carried out at 5000 rpm for a further two hours. Once this period has elapsed, a mixture of chitosan (0.85 g), demineralized water (50.4 g) and glacial acetic acid (0.43 g) is added.
• the stirring conditions are maintained for a further two hours at an autogenous temperature value of about 60°C.
• a mixture of benzalkonium chloride salt (5.1 g) solubilised in water (5.1 g) is added.
• the whole mixture is stirred for a further two hours until an aqueous dispersion based on graphene oxide is obtained, which is used in subsequent bactericidal tests.
• This nanodispersion after the addition of an amount of Adesital primer equal to 5 % by weight of the whole mixture, is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2. Once the depositions have been carried out on the slide with the nanodispersions, it is allowed to dry for about 12 hours in order to favour the fixation of the nanodispersion on the glass surface. The slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• the nanodispersion described above after adding an amount of San Marco primer equal to 5 % by weight of the whole mixture, is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• the slide Once the depositions have been carried out on the slide with the nanodispersions, it is allowed to dry for about 12 hours in order to favour the fixation of the nanodispersion on the glass surface.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 3 synthesis of dispersion 03 (017PN/20/l- ⁇ reference bactericidal test with Adesital primer; 023PN/20/1 Preference bactericidal test with San Marco primer)
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 1.5 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70°C.
• a second aliquot of hydrogen peroxide 30 % weight/weight Sigma Aldrich (40.4 g) is thus added, in which 0.43 g of solid silver nitrate Sigma Aldrich is dissolved.
• Mixing is carried out at 5000 rpm for a further two hours. Once this period has elapsed, a mixture of chitosan (2.55 g), demineralized water (49.3 g) and glacial acetic acid (2.55 g) is added.
• the stirring conditions are maintained for a further two hours at an autogenous temperature value of about 60°C.
• a mixture of benzalkonium chloride salt (4.25 g) solubilised in water (4.25 g) is added.
• the whole mixture is stirred for a further two hours until an aqueous dispersion based on graphene oxide is obtained, which is used in subsequent bactericidal tests.
• This nanodispersion after the addition of an amount of Adesital primer equal to 5 % by weight of the whole mixture, is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2. Once the depositions have been carried out on the slide with the nanodispersions, it is allowed to dry for about 12 hours in order to favour the fixation of the nanodispersion on the glass surface. The slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• the nanodispersion described above after adding an amount of San Marco primer equal to 5 % by weight of the whole mixture, is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• the slide Once the depositions have been carried out on the slide with the nanodispersions, it is allowed to dry for about 12 hours in order to favour the fixation of the nanodispersion on the glass surface.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 4 synthesis of dispersion 04 (024PN/20/1 preparation code; 033PN/20/1 code of bactericidal tests at 25 % (033PN/20/1-3, 50 % (033PN/20/1-2, 30 % (36PN/20/1-4, 95 % (36PN/20/1-2/ 1st inoculum), 95 % (36PN/20/1-2/ 2nd inoculum), 95 % (36PN/20/1-2/ 3rd inoculum), 50 % (36PN/20/1-3 1st inoculum), 50 % (36PN/20/1-3 2nd inoculum) , 50 % (36PN/20/1-3 3rd inoculum),
• Nano 27 graphite marketed by Asbury Carbons (HSAG) 5 g
• demineralized water 200 g
• a mixture composed of chitosan Sigma Aldrich (0.50 g)
• demineralized water 49.5 g
• glacial acetic acid Sigma Aldrich 0.06 g
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 1.5 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70°C.
• a first aliquot of hydrogen peroxide 30 % weight/weight Sigma Aldrich (112.0 g) is added while keeping stirring.
• it is mixed for approximately one hour and then a second aliquot of hydrogen peroxide 30 % weight/weight Sigma Aldrich (40.0 g) is added in which 0.50 g of silver nitrate Sigma Aldrich, and glacial acetic acid Sigma Aldrich (3.8 g) are dissolved.
• This nanodispersion is divided into three different aliquots in which three different quantities of Adesital GS primer equal to 5%, 50% and 70% by weight of the whole mixture are added.
• the solutions thus obtained are stirred with magnetic stirrers for a period of three hours. At the end of this period, subsequent depositions of these products on previously prepared microscopy slides are carried out, as described in point 2.
• Example 5 synthesis of dispersion 05 (032PN/20/1 preparation code; 40PN/20/1-1 code of bactericidal tests)
• Nano 27 graphite marketed by Asbury Carbons (HSAG) (4.7 g)
• demineralized water (306.2 g)
• hydrogen peroxide 30% weight/weight Sigma Aldrich (160.14 g).
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 3 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70°C.
• an aqueous dispersion based on graphene oxide is obtained, which is used in subsequent bactericidal tests.
• This nanodispersion after adding an amount of Adesital GS primer equal to 5 % by weight of the whole mixture is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 6 synthesis of dispersion 06 (034PN/20/1 preparation code; 40PN/20/1-2 code of bactericidal tests)
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 3 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70°C.
• This nanodispersion after adding an amount of Adesital GS primer equal to 5 % by weight of the whole mixture is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• Example 7 synthesis of dispersion 07 (039PN/20/1 preparation code; 40PN/20/1-3 code of bactericidal tests)
• Nano 27 graphite marketed by Asbury Carbons (HSAG) (4.0 g) and demineralized water (252 g).
• HSAG Asbury Carbons
• demineralized water 252 g.
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 0.5 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70 0 C.
• This nanodispersion after adding an amount of Adesital GS primer equal to 5 % of the whole mixture is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 8 synthesis of dispersion 08 (041PN/20/1 preparation code; 40PN/20/1-4 code of bactericidal tests)
• Nano 27 graphite marketed by Asbury Carbons (HSAG) (4.0 g) and demineralized water (220 g).
• HSAG Asbury Carbons
• demineralized water 220 g.
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 5000 rpm.
• the system is kept under these conditions for 0.5 hours by monitoring the increase in autogenous temperature, which reaches a value of approximately 70 0 C.
• This nanodispersion after adding an amount of Adesital GS primer equal to 5 % by weight of the whole mixture is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 9 synthesis of dispersion 09 (048/PN/20/1 bactericidal test code performed with 5 % and 75 % Primer)
• Nano 27 graphite marketed by Asbury
• polyethylene glycol Sigma Aldrich (4 g) is added and stirred for two hours at a temperature close to 70°C. After this period, 136 g of hydrogen peroxide 30% weight/weight Sigma Aldrich is added, continuing stirring for a further three hours. In this way an aqueous dispersion based on graphene oxide which is used in subsequent bactericidal tests is obtained.
• This nanodispersion after adding an amount of Adesital GS primer equal to 5 % by weight of the whole mixture is stirred for a period of three hours. At the end of this period, subsequent depositions of this product on previously prepared microscopy slides are carried out, as described in point 2.
• the slide Once the depositions have been carried out on the slide with the nanodispersions, it is allowed to dry for about 12 hours in order to favour the fixation of the nanodispersion on the glass surface.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out bactericidal tests.
• Example 10 synthesis of dispersion 10 (068/PN/20/1 bactericidal test code performed with 5 % of two different primers)
• Nano 27 graphite marketed by Asbury
• HSAG Carbons
• demineralized water 312 g
• polyethylene glycol-400 Sigma Aldrich 9 g
• Silver Nitrate marketed by Sigma Aldrich.
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 6000 rpm.
• the system is kept under these conditions for 1 hour by monitoring the increase in autogenous temperature, which reaches a value of approximately 60°C.
• demineralized water (306 g) is added during about 20 minutes by means of a dropping funnel, continuing then to mix the entire reaction mixture for a further hour.
• the slides thus obtained do not release the substance deposited on them and are therefore considered suitable for carrying out bactericidal tests.
• Example 11 synthesis of dispersion 11 with conventional stirring (no Silverson)
• Example 10 is repeated in its entirety by using conventional stirring by means of mechanical blades. The result obtained at the end of this process leads to obtaining unstable mixtures which give rise to phase separation.
• Example 12 synthesis of dispersion 12 (086/PN/20/1 bactericidal test code carried out with 5 % San Marco Primer)
• HSAG Carbons
• demineralized water 385 g
• hydrogen peroxide 30% weight/weight Sigma Aldrich
• polyethylene glycol-400 Sigma Aldrich 6.5 g
• acetic acid 6.5 g
• Silver Nitrate 1.3 g
• the Silverson mixer is immersed in the reactor and subsequently set at a stirring speed of 6000 rpm.
• the system is kept under these conditions for 1 hour by monitoring the increase in autogenous temperature, which reaches a value of approximately 60°C.
• the slide thus obtained does not release the deposited substance and is therefore considered suitable for carrying out tests for the evaluation of antibacterial and antiviral properties.
• compositions of Examples 1- 10 and 12 are shown in Tables 1 - 3.
• the first control sample consisting of the slide covered with Adesital primer only, returned a value coinciding with the inoculation value. For this reason, 5 this material was considered as the reference blank relative to which to compare the bactericidal action of all preparations.
• Table 5 summarises the results of the antiviral plaque assay test conducted after 2 or 4 hours of incubation with SARS-CoV-2 virus.
• Table 6 shows the results of the antiviral plaque assay test conducted at time 0 compared with the results obtained after 2 hours of incubation.

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Plant Pathology (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)
• Paints Or Removers (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=75769917

Family Applications (1)

Country Status (7)

Families Citing this family (2)

Family Cites Families (7)

• 2021
  • 2021-02-25 IT IT102021000004457A patent/IT202100004457A1/it unknown
• 2022
  • 2022-02-23 EP EP22706686.7A patent/EP4298167B1/de active Active
  • 2022-02-23 CA CA3201206A patent/CA3201206A1/en active Pending
  • 2022-02-23 ES ES22706686T patent/ES3051357T3/es active Active
  • 2022-02-23 CN CN202280016774.6A patent/CN116940641B/zh active Active
  • 2022-02-23 US US18/547,282 patent/US20240166896A1/en active Pending
  • 2022-02-23 WO PCT/IB2022/051568 patent/WO2022180521A1/en not_active Ceased

Also Published As

Similar Documents

Legal Events